Escalerosia igori, Alekseev, Vitalii I. & Grzymala, Traci L., 2015

Alekseev, Vitalii I. & Grzymala, Traci L., 2015, New Aderidae (Coleoptera: Tenebrionoidea) from Baltic and Bitterfeld amber, Zootaxa 3956 (2), pp. 239-257 : 242-243

Escalerosia igori sp. nov. Alekseev & Grzymala

( Figs. 1–7 )

Material examined. Holotype No. 217-2 [ CCHH], male ( Figs. 1–4 ). The beetle inclusion is preserved in a polished piece of transparent amber with a yellowish shade and the amber piece is embedded in polyester resin. Syninclusions are absent. Paratype No. 881-2 [ CCHH], possible female ( Figs. 5–7 ). The beetle inclusion is preserved in a polished piece of transparent amber with a yellowish shade and the amber piece is embedded in polyester resin. Syninclusions are absent. Paratype No. 890-4 [ CCHH], male. The beetle inclusion is preserved in a polished piece of transparent amber with a yellowish shade and the amber piece is embedded in polyester resin. Syninclusions are absent. Paratype No. 1006-1 [ CCHH], sex unknown. The beetle inclusion is preserved in a polished piece of transparent amber with a reddish shade without any further fixation. The piece is elongate, with maximum length 31 mm and maximum width 15 mm. The plant syninclusions are represented by many trichomes (“stellate hairs”) and the animal syninclusions are represented by five Collembola and one dermestid beetle ( Coleoptera : Dermestidae ) 2.1 mm in length. Paratype No. 10 [CAB], possible female. The beetle inclusion is preserved in a polished piece of transparent yellow-orange amber without any further fixation. The piece is conical, with maximum length 34 mm and maximum width 23 mm. The syninclusions are represented by four trichomes and differently sized pieces of woody material.

Etymology. Patronymic, this new species is dedicated to the father of the first author—Igor N. Alekseev (1952–2009).

Type strata. Baltic Amber. Eocene.

Type locality. Russia, the Kaliningrad region, the Sambian [Samland] peninsula, Yantarny settlement [formerly Palmnicken].

Description. Length: 1.6–2.5 mm (No 217-2—2.0 mm; No. 881- 2—2.5 mm; No. 890-4— 2.2 mm; No. 1006- 1 —2.2 mm; No. 10— 1.6 mm); moderately convex, elongate. Brown-piceous, appendages light rufous. Upper surface biseriate, clothed with very short pubescence, one seta arising anterad of each puncture, with additional short, numerous setae between primary pubescence (pruinose pubescence). Body length 2.5× maximum body width. Elytral length 2.6× pronotal length.

Head. Eyes large, oval, with slight anterior emargination, well-separated from hind margin of head; interocular space narrower than one ocular diameter; temples approximately 1/3 of ocular diameter; frons and vertex without punctures; maxillary palpomeres orange, apical palpomere broad, triangular, slightly rounded; apical labial palpomere expanded. Antenna filiform, robust; 11-segmented, pubescent; reaching basal third of elytra when folded backward; antennomere III shortest, antennomere XI longest; antennomere length ratios: 5-5-4-5-5-5-6- 6-6- 6-10; antennomeres VII–X asymmetrical, slightly serrate ( Fig. 1 B).

Thorax. Pronotum slightly wider than long, widest subapically, with anterior raised tubercles; disc with irregularly spaced fine punctures; with two small pits at basal angles ( Fig. 1 A). Base of prothorax distinctly narrower than combined elytral bases. Scutellum campanulate, widest basally. Elytron moderately convex; sides weakly rounded; width 0.67× length; pubescence very short; punctation moderate, fine. Metathoracic wings present.

Abdomen. Separation of abdominal ventrite I and abdominal ventrite II apparent laterally, completely obsolete in medial third.

Legs. Metafemur with comb of thick setae, confined to apical 2/3 of metafemoral length and 1/3× metafemoral width ( Figs. 4, 6 ). Metatarsomere I approximately 1.5× longer than metatarsomeres II–IV combined, metatarsomere II bilobed; metatarsomere III visible ( Fig. 1 C).

Diagnosis. Escalerosia igori sp. nov. differs from the African Escalerosia acutithorax (Escalera 1922) by the more prominent anterior tubercles, by the very short, indistinct pronotal pubescence, and by the irregular pronotal punctation.

Note. This newly described species is found within Danish and in true Eastern (Sambian) Baltic amber. The fossil species is variable in color and pronotal relief. Specimen 290-4 is darker, unicolorous and has the pronotum with more expressed tubercles and the median impression with deeper, more distinct punctures. We interpret these characters as polymorphic within the single species here described because other significant morphological differences were not found.

Figures

FIGURE 1. Escalerosia igori sp. nov. holotype illustrations. A. forebody, B. antenna, C. metatarsomeres.

FIGURES 2 – 7. Escalerosia igori sp. nov. habitus photographs. 2) Holotype, dorsal view; 3) Holotype, ventral view; 4) Holotype, close-up of legs and abdominal ventrites; 5) Paratype (No. 881 - 2), dorsal view; 6) Paratype (No. 881 - 2), ventral view; 7) Paratype (No. 881 - 2), lateral view. Scale bars = 0.5 mm for 2 & 3, 0.2 mm for 4, 1.0 mm for 5 – 7.